For film, glyoxal or chrome alum or both in a mixture, but for plates only chrome alum is suggested.

Be careful of chrome alum with some sensitizing dyes. It will harden faster with some dyes due to an interaction of some sort. I have had one small batch with chrome alum set up on me during the coating session.

??? and Double ???

Originally Posted by Photo Engineer

Ray;

We did something similar at Kodak. You test samples for the maximum amount of sulfur + gold and the maximum time and the maximum temperature. It is an emulsion factor we call EOF or Extent Of Finish and is measured in KCal / mole of silver. So our method, while similar is quantized.

PE

???

What did you measure?
The actual incorporation of S+Au vs. time and temperature?
While My Chemistry Gently Sleeps, I must ask, do you actually measure KCal or just calculate it?

How we get KCal out of density data?

Are you talking about the standard enthalpy of formation or (standard heat of formation) and if so which compound?

You run a series at different levels of S/Au, temperature and time. The measurements are speed and fog. From the optimum time and temperature, you can derive Kilo Calories input / mole of silver. If you then vary the temp/time or rise and fall profile, but keep KCal / mole constant, the finish should give about the same result but with slightly altered properties. I don't intend to go into detail any more than this. It is one of the little factors that those who say they "know a lot about emulsions" never seem to get around mentioning.

Just as we had models to work with making and scaling emulsions, we had a computer program which did all of this for us. Unfortunately, I am reduced to doing this all by trial and error, and at great cost in time and silver nitrate.

its a joke

Originally Posted by Photo Engineer

Just as we had models to work with making and scaling emulsions, we had a computer program which did all of this for us. Unfortunately, I am reduced to doing this all by trial and error, and at great cost in time and silver nitrate.

PE

Are you bragging or complaining?!!

The fact that you had the people and equipment to help you model, predict and compute must have made you lazy!

Golly Ned Ray! My aqueous humor is tearing me apart. (pun there for those that get it)

No one has given me a hard time Ray. They just avoid the topic and allude to their "vast knowledge" when it is really "half vast". 'Nother pun. Finish has been largely ignored in the posts here, and rightly so as it is arcane and was really outside of my main area of expertise. I was writing finish model programs when I retired and it kept going after I left. I can do them, and know what is going on, but I don't know the details of the more complex varieties used in some cases.